Apparatus for drying excavations



Oct. 6, 1953 J. T. CULLETON APPARATUS FOR DRYING EXCAVATIONS 2Sheets-Sheet 2 Filed June 10, 1950 INVENTOR. T. CULLETON fifib JOHNATTORNEY Oct. 6, 1953 J. T. CULLETON APPARATUS FOR DRYING EXCAVATIONS 2Sheets-Sheet 1 Filed June 10. 1950 I INVENTOR. JOHN T- CULL E TON 3WATTORNEY Patented Oct. 6, 1953 UNITED STATES APPARATUS FOR DRYINGEXCAVATIONS John T. Culleton, Hayward, Calif., assignor to PacificPumping Company, Oakland, Calif., a corporation of CaliforniaApplication June 10, 1950, Serial No. 167,439

4 Claims.

This invention relates to an apparatus for keeping seepage waterexhausted from excavations or ground areas which are lower than thegenerally prevailing water level.

The invention has particular application to construction projects, suchas tunnels, sewers, bridge pier foundations, etc. When a tunnel is to bebuilt in a ditch or a bore, the contractor is often plagued by waterwhich seeps into the ditch or bore from one source or another and makesit impossible to do the work unless the water can be kept out during theconstruction period.

For many years, this water has been controlled somewhat by a methodemploying a plurality of well points connected to a header which in turnis connected to one or more high-vacuum pumps.

The method of the present invention achieves a distinct advance over theold method and solves problems which have interfered with the efficiencyand the satisfactory use of the old method.

One of the problems solved is that with the new method when the areaaround a well point goes dry, so to speak, and air is sucked into theline through the well point, there is no interference with theefiiciency or working of the other well points in the system. With theold suction pump and header method, when one or more well points wentdry, the minus pressure (suction) of all the other well points woulddrop 3 and so would diminish their ability to pick up water and carry itup to the pump. Different plans have been tried in the past with the oldmethod to shut ofi a particular well point suction line as soon as theoperator became aware that its well point was sucking air. In the firstplace this has meant an operator inconstant attendance on the system andhe has tried by watching glass tubes set in the suction line or by earto detect which well point lines should be shut oil. The present methodeliminates the need for an operator in constant attendance and providesa fool-proof, automatic dewatering system. This is not only an economyto all concerned, but the increased efficiency of the new system keepsholes dry which before never could be kept perfectly dry.

In describing the method, a suitable apparatus has been shown in thedrawings, in which:

Fig. l is a schematic view in perspective showing the system as appliedto a ditch;

Fig. 2 is a detail View in elevation,. partly in section, showing a formof individual jet pump and a form of well point; and

Fig. 3 is a like view of a form of air release.

In using these forms of devices to illustrate the application of mymethod and apparatus, I do not intend thereby to limit it, except as isrequired by the appended claims.

The apparatus shown in Fig. 1 includes a centrifugal pump I I! (normallyclassified as a vertically-split case or a horizontally split-case)driven by any suitable available power source I I. In this case it is anelectric motor. The inlet [2 of the pump I is connected by a pipe to anair separation chamber and reservoir l4 for starting the system after ashutdown. The outlet of the pump I0 is connected to what I call a' highpressure header 16 from which the leads H, H, H, i! run to theindividual jets l8 (see Fig. 2), each of which is positioned above andconnected to the outlet of a well point l9. Shut off valves 20 in eachlead 11 facilitate selection of the well points to put in service.

The well point 19 (see Fig. 2) includes a pipe 2! having an opening orseries of openings 22, surrounded by a fine screen 23 with a heavierprotecting screen 2311 around the whole. The outlet 24 of the well pointis connected to the chamber 25 in the jet housing 26 by the pipe 21.This chamber surrounds the jet nozzle l8 and opens into the jet venturi28, so that when the water or other liquid being pumped through theheader i6 rushes from the nozzle !8 it creates a vacuum in the Venturitube 28, thus lowering the pressure in the well point l9 and causing thewater 29 around the well point to flow in through the screens, up intothe Venturi chamber 25 and into the Venturi tube 28. There it mixes withthe water from the nozzle [8, and the total of nozzle capacity and flowthrough the well point passes on up through the pipe 30 into the returnor low pressure header 3! and into the reservoir l4. 7

On the return header 3|, at its highest point where air will collect, Iprefer to put an automatic air vent valve 32, having a float 33 on anarm 34 which opens and closes the valve disc 35 on the outlet orifice 36(see Fig. 3)

So long as water fills the system, the float remains buoyed up and holdsthe valve disc to its seat. As air accumulates, it displaces the waterin the body of the valve and the float falls as the water recedes, thuspulling the disc off its seat. The accumulated air is then discharged bythe pressure in the system. As the water rises in the body, the floatreturns the disc to its seat, and prevents water from escaping. When aircollects again, the cycle is repeated. On a header 3| which is 4110 feetlong there may be several of these air vent valves 32.

On each return line 30 is a valve 31 to be closed whenever the valve 20on the pressure line I! is closed. This would be at a time when anyparticular well point was to be inactivated.

In an installation each set of branch leads I! and 30 are usually about5 feet apart from the next set, but this distance may be varied to suitthe volume of water that has to be withdrawn from the excavation.

The water picked up through the well points l9 represents-a surplusover; that being pumped down the line H, and will flow out the overflowof the tank l4, leaving in the tank all the liquid needed to keep thesystem primed and the header l6 and pipes l1 filled. The over flow isplaced at a point higher than the inlet of the pump 10.

I have found that the systemaworkshwell with a pressure of 55 to 70poundsinthe high pres? sure header l6 and with a pressure of to 15pounds in the return or low pres sur e header -fil. The centrifugal pump[0 has to bebig enough to supply the demand of the combined capacitiesof the jet nozzles I8. Any number of these nozzlesxmaybeusedso long asthe pump 10 has therequiredoutputa:g I 1 My new ,-system ,o,f dewateringis raccon plished byf theuse of a pluralityof ,jetsJB connected as .1.herein setforth sqthat if one or more wellpcints r'.l,9.s-have exceededthe flow of waterinto them through the openings, 22 and, are taking,in;;air, .-this will in nowaysaffectwor decrease,-the-;,efiiciencygofthe other wellpoints which are still -,-,;submerged ,inawater; It was;;this discov this-new -method which solved the old p oblem, winherent invacuum pumping, namely that when .Onepnmore well points began sucking,in air, the vacuum in the whole system decreasedand erefQre; th amount:-V?Q E;:: KQQ 9; v sthroug-h thewell p.oints-;still submerged; waterdropped ofi, Zi'his meantthat in the old-method itwasnecessary,toexercise constantwigilance over the well; points;so thatthose-that w re glry,

e e h m n ou ib i fi p ans-yew.- hy a valve, Glass tubestorsighting.,-to detect we when awell point went :dry, and-listening todetermin if-a mr ateLW fl wi iqn y a: 1. a ti ula "W911; 1 1 l-"13. 55:tam

we estr e i n e 101d me hod ,i h b i l ;Bv-- t e w em d r ea er nir swnpossible to cut -downvon the laboriorcenecessary t ,,;k P;. Z Q-. s st me in and i i efi ;1.f;I1 $.ib f Il a;.-iq to 1 p awa ,a di ve te at n ua ten d: y r.th lws k-eh n fi r le periods of time. This was unheard ofwith the s s ms n nnother yery distinct advantage .of ,t u

method is that it can be used in an excavation ide t sim l byvwnning hele om 7 the high 5 pressure ihea der ..i 6 I tusually, at the s r ace eiM-an h -p d roeia turnheader ,3], usuallyl also at the surface level)down into-.the,e xca-vationv no matter what tse e ih W il the m J han h{reservoir M ar kept un-on th wqrk n evelwh reth y are ,easy -to watchand to. repair, With th'e'gold ys m, ofu in m eh n calmi ps to: l f ywater the l to 20 foot lift possible withfv ac ium madeit necessaryinany ,excavation of 15 2 t,- feet to? put ,another complete well point 1:sys m at th W0. f t l e I s [st qperated entirely independently ofthefsystem at thehigher levellgf fhis visgcalled stagingland there hadto ,be, .as many independent ,systems, one at each stage, as thereweremultiples of feet inthe, depth of the excavation. in l.Thisindicates-too thatin-deep excavations under .-the old method ofstaging, thewcost of equipment goesup as each additional independem:units'r Sie v improved system also dispenses with the vaeuum pumpwvhich wasneeded on the old The net eifect of this new syste n is that it keepsthe water level down below grade, "drying 4 up the sub-grade so thecontractor is working the dry It does this withgangindividual jetinstalled at' each wel'lfipointli Noirialtter whether one or twenty wellpoints are sucking part air 5,;with the water, or even all air, thisdoes not a fgiect th performance of the system.

Nomatter whether the excavation is twenty .-.-g0r ;orty,;i'-eet deem;the supply pipes can still be for the ground surface, with just theindividual 10 lines going down to the well points, because the actual,pumping, is done right above the point with the jet. This keeps thepiping out of the way;- .completed sections can have the points removedand the excavation backfilled, with the 15: rPQZP-P *s PQY Qn PP QEQF;ne h l wit u disturbing the supply pipes.

f device. .of claim} together," with "a 'Q'fioat controlled air releasemeansin the fluid return 11118,, .3

i lsc n c e 7 1d, rese voir he mean ,the 4 level I pf he" inlet to saidcontinuous fluid ing 3 inj which Zsaid "clonland aid'i ui po spcsed ator hear the id excavation.

" a ground level alongside v 'faomr T; "cunLnrroN.

